The dynamic range of broadband digital system is mostly limited by harmonics and spurious arising from ADC nonlinearity. The nonlinearity may be described in several ways. The distinction between static and dynamic contributions has strong theoretical motivations but it is difficult to independently measure these contributions. A more practical approach is based upon analysis of the complex spectrum, which is well defined, easily measured, and may be used to optimize the ADC working point and to somehow characterize both static and dynamic nonlinear-ity. To minimize harmonics and spurious components we need a sufficient level of input noise (dither), which de-stroys the periodicity at multistage pipelined ADC, com-bined with a careful analysis of the different sources of nonlinearity.